Thread severing means for sewing machines



Aug. 28, 1962 J. CORTESE ETAL 3,051,111

THREAD SEVERING MEANS FOR SEWING MACHINES 2 Sheets-Sheet 1 Filed June 24, 1960 Aug. 28, 1962 J. CORTESE EI'AL 3,051,111

THREAD SEVERING MEANS FOR SEWING MACHINES Filed June 24, 1960 2 Sheets-Sheet 2 3,%l,l l l Patented Aug. 28, 1962 3,051,111 AD SEVERING MEANS FOR SEWING MACHINES Joseph Cortese, Union, NJ and Joseph Volhnan, de-

ceased, late of Union, NJ, by Victor H. Eichhorn, administrator, Elizabeth, NJ, assignors to The Singer Manufacturing Company, Elizabeth, N..l., a corporation of New Jersey Filed June 24, 1960, Ser. No. 38,654 6 Claims. (Cl. 112252) The present invention relates to sewing machines and' particularly to means for automatically severing the sewing thread at the completion of the sewing operation in a cyclically-operated chain stitch sewing machine.

Cyclically-operated machines or, as more commonly known, tacking machines are usually provided with means for cutting or breaking the sewing thread at the completion of the sewing operation. In a cyclicallyoperated sewing machine of the single thread chain stitch type, e.g., a button sewing machine, there is only one sewing thread. Conventionally, this thread has been severed by breaking it as the work clamp is raised to remove the completed work piece. In the final stitch of the cycle, the machine is stopped by the stop-motion mechanism with the sewing thread running from the needle, through the work, about the loop seizing beak of the looper, and to the last stitch in the work. A thread nipper is actuated at this time to prevent drawing thread from the supply. When the work clamp is raised to its highest point, the pull on the thread causes it to break at the knot formed by the last stitch set in the work.

While this thread severing means has been successfully used for many years, it has a disadvantage in that it is relatively slow since the thread severing is accomplished only during the last portion of the work clamp raising motion. This disadvantage is pronounced in machines having, for example, automatic button loading mechanisrns particularly of the type disclosed in the United States patent of Willis et al. No. 2,921,544, January 19, 1960, since the operator cannot remove the work from the machine until the work clamp is raised sufiiciently high to break the sewing thread. 'Since the only function required of the operator in such a machine is to position the work relatively to the machine, this waiting for the machine to stop and the work clamp to raise to its highest position reduces production.

In accordance with the above, the primary object of the present invention is to provide a thread severing means for a single thread chain stitch sewing machine that will operate independently of and prior to the lifting of the work-clamp, thereby permitting removal of the completed Work immediately upon termination of the sewing cycle and the raising of the work clamp sufficiently to release the Work. No longer is it necessary to wait until the work clamp is fully open. Further objects of this invention are to provide such a thread severing means that is economical, eflicient, dependable and durable.

Having in mind the above and other objects that will be evident from an understanding of this disclosure, the invention comprises the devices, combinations and arrangements of parts as illustrated in the presently preferred embodiment of the invention which is hereinafter set forth in such detail as to enable those sk lled in the art readily to understand the function, operation, construction and advantages of it when read in conjunction with the accompanying drawings in which:

FIG. 1 is a rear elevational view of a sewing machine embodying the present invention.

FIG. 2 is a fragmentary end elevational view of the sewing machine of FIG. 1 with parts broken away and in section to illustrate more clearly the stop motion mechanism of the machine.

FIG. 3 is a fragmentary vertical sectional view taken substantially on the line 33 of FIG. 1 and illustrating the mechanism at the thread severing point in the cycle.

FIG. 4 is a fragmentary sectional view taken substantially on the line 4-4 of FIG. 1.

In accordance with the present invention, there has been provided a means for severing a sewing thread by breaking, which means is actuated by a predetermined overthrow designed into the stop motion mechanism that brings the machine to a stop upon completion of the sewing cycle. t

The present invention is herein illustrated as applied to a class 114 Singer sewing machine such as illustrated in the United States patent of McCann, No. 2,300,585, November 3, 1942, to which reference may be had for a more complete understanding of the machine. The particular machine herein illustrated and described is a cyclically operated single thread chain stitch sewing machine fitted to sew buttons onto a work piece.

With reference to the drawing, the illustrated sewing machine comprises a frame including a base 1, a cylindrical work-supporting bed 2 extendingfrom said base in cantilever fashion, a standard 3 rising from said base and carrying a bracket arm 4 overhanging the bed 2 and terminating in a head 5. A main shaft 6 is journaled longitudinally of the bracket arm 4 and on the end thereof beyond the standard 3 is provided with a driving pulley 7 secured thereto and an idler pulley 8 journaled thereon. Power is delivered to the machine by means of a belt 9, FIG. 2, that is adapted to be shifted between the driving pulley 7 and idler pulley 8.

The stitching mechanism of the machine comprises a needle 10 mounted upon the lower end of a needle bar 11 that is mounted for endwise reciprocation in the head 5 and driven by connections (not shown) from the main shaft 6. Cooperating with the needle 10 in the .clamp 15 from the lower plate formation of single thread chain tional rotary wing-type looper 12 of a bed shaft 13 journaled in connections (not shown) from As illustrated in FIG. 3, the ample, two plies of material plate 14 of a work clamp 15 by a pair of button clamping jaws 16 in which is held a button B to be sewed to the material W. During the operation of the machine, the work clamp 15 is moved laterally so that upon alternate stitches the needle 10 will penetrate the opposite holes of the button B. For sewing four hole buttons, the work clamp 15 is also moved endwise of the bed 2 after a predetermined number of stitches in the first pair of holes in the button to sew through the second pairof holes the button. The work. clamp 15 is moved through'mechanism driven by a cam 17 secured on a counter shaft 18 journaled transversely of the standard 3 and driven from the main shaft 6.

For lifting the button clamping jaws 16 of the work 14 there is provided a clamp lifting bar 19 mounted for endwise sliding in the head 5 and having a laterally extending arm 20 secured to the lower end thereof. The arm 20 is adapted to engage under an arm 21 secured to the pivotally-mounting sl1nporting bar 22 that carries the button clamping jaws f6. The clamp lifting bar 19 is raised by a presser lifter lever 23 pivotally mounted by a bracket 24 on the top of the bracket arm 4. The one end of the lever 23.is connected to a collar 25 on the top of the bar 19 while the other end is adapted to be connected by a chain or rod 26 to an actuating mechanism.

The machine is also such as disclosed in the stitches is a convenmounted upon the end the bed and driven by the main shaft 6.

work comprises, for ex- W clamped on a lower provided with a thread nipper 27, above noted Patent No. 2,300,585.

Briefly, this thread nipper includes a lever 28 that is adapted to be actuated by a cam lobe 29 on the cam 17 7 through a bell-crank lever 34} and link 31. The sewing thread T from the source passes successively through a first tension device 32, a second tension device 33, then through a series of guides to the take-up eye '35 on the a needle bar 11 and then to the needle 10.

. Fifield, No. 1,498,649,1une 24, 1924. The stop motion mechanism 36' comprises a bracket 37 secured to the end of the standard 3 and having a socket 38 that receives anoscillatin'g'cylinder 39 in'which a stop lever 40 is pivotally mounted by a pin 41. The stop lever 40'carriesa belt shifter 42' for moving the "driving belt 9 between the pulleys 7 and 8. Telescoping into the upper end of the stop lever 40 is a spring-pressed plunger 43 (see United States patent of Fifield No. 1,184,337) that is adapted to engage a stop cam 44 secured to the driving pulley 8. The stop lever 40 is normally biased aboutthe axis of the cylinder 39against a lug 45 of the bracket 37 by a springpressed plunger 46.

In the stoppedposition, the stop lever 40 is'positioned, as .shown in FIG. 1, with the-plunger 43 in :cooperation with the stop cam 44. ,The' stop lever 40 is biased into this position by a tension spring 47, one end of which is secured to the lower end of the 'stoplever and the other end of which is secured to the base'l. To initiate operation of the machine, the stop lever 40 is moved pivotally aboutthe pin 41 against the action of the spring 47 tomove the plunger 43 out of cooperation with the stop cam 44 and simultaneously shift the belt 9 by means of thebelt shifter 42 :from theidler pulley 8. This move:

. ment of the stop lever 40 is accomplished by means of a starting lever 48 pivotally mounted on the bracket 37 by means of a, pivot pin 49 and having a first arm 50 con nected by a pull rod or chain 51 to any desired starting device, either operator actuated or automatic, and having a s'econdarm 52 that engagesthe stop lever 40. The stop lever 40 is held in this position during the sewing cycle by a spring pressed latch 53., Upon completion of the sewing cycle, the latch 53 is tripped by an arm 53a on the cam 17 to release the stop'leve r'40 which'then, under the action of the spring 47 moves to place the plunger 43 into cooperation withthe stop cam.44 and simultaneously therewith the belt shifter 42 moves the belt 9 from the driving'pulley 8 to the idler pulley 7.

' 'The stop cam 44 is formed for the most part with a spiral surface 54 that leads to a notch 55' and a stop surface 56., The stop lever 40 is designed to be released when the plunger 43 is opposite the point of minimum diameter on the spiral surface 54 of the'stop cam. Thus,

. asthe stop cam '44 continues to rotate as the machine is coasting, the spiral surface 54'depresses the plunger 43 which action tends to exert a braking influence on the machine.- To increase the braking action, there is provided in the, illustrated machine a separate brake comprising -a lever 57 pivotally mounted on the bracket 37 and at its'upper end having a brake element 58 adapted to engage the driving pulley 8 and at its lower end connected to one] end of a tension'spring 59. When the continued rotation of the stop cam 44 under the coasting of the machine brings the stop surface 56 against the plunger 43,

the stop lever 40 is driven about the axis of the cylinder 7 39. against the resilient action of the plunger'46. The

forward rotation of the machine is thus stopped and'during this time, the stop lever is deflected from the normal position illustrated in dotted lines in FIG. 2, which is determined by engagement :of the stop lever 40 against the log 45, to the'full line position in FIG. 2. Under the action of the spring pressed plunger 46, the stop lever 40 is then immediately returned to the dotted line position of FIG. 2 which is the normal position when the machine is not in operation. I V I a V The normal position of the looper 12 when the machine is stopped, i.e., the position corresponding to that represented by the dotted line position of the stop lever 40 in FIG. 2, is illustrated by the dotted line position in FIG. 3. During the deflection or overthrow of the stop lever 40 from the dotted to'the full line positions of FIG. 2, the

looper 12 is correspondingly advanced from the dotted v line to the full line position of FIG. 3.

Upon each rotation of the looper 12,. a loop of the thread T is seized from the needle 10. The stopped position illustrated in dotted lines in FIG. 3 is shortly beyond the loop seizing position of thelooper '12so that at this a point in the sewing cycle, the thread loop has been entered by the loop seizing beak 60 of. thelboper and is seated in the throat 61 at the base of the beak 60. Atthistime.

the needle bar 11 with its take-up eye 35. is approaching the top of its stroke and the previous stitch has been substantially set in the work by the take-up action of the needle-bar and the thread drawing action of the looper;

Thus, during the normal stitching cycle, thread is drawn into the system through the tension devices 32 and 33 as the looper 12 advances beyond the dotted line position of FIG. 3. Thread nipper 27 is actuated at this time and prevents drawing thread from the supply. In addition, the overthrow of the looper 12 from the normal inoperative position is designed to be great enough to overcome the normal elasticity of the thread and'tostress the same beyond the breaking point. At the point from which the thread emerges from the last stitch in the work, it is bent sharply about other portions of the thread,.so that when the thread is stressed by the overthrow of the looper 12, itinvariably breaks at exactly this point, substantially as illustrated in FIG. -3. In this manner, not only is the thread severed such as to eliminate a thread end but also there is provided an adequate thread lead on the needle which permits starting the next stitching cycle-without unthreading the needle. At the same time, the thread breakage occursindependently of and before the work clamp is raised so that the operator does not have to Wait until the work clamp'is raised before the work can be removed from the machine.

Numerous alterations of the structure herein disclosed will suggest themselves to those skilled in the art. However,- it is to be understood that the present disclosure relates to a preferred embodiment of my invention which is for purposes of illustration only and not to be construed as-a limitation of the invention. All such modifications which do not depart from the spiritof the invention are intended to be included within the scope of the appended claims.

Having thus set forth the nature of we claim herein is:

1. In a cyclically operated sewing machine having stitching mechanismincluding a needle and a loop taker cooperating with the needle in the formation of stitches, said loop taker having a stitch-forming cycle wherein a loop of thread thrown by said needle seized bysaid loop taker and thereafter expanded by a thread drawing action during which thread is drawn into the thread system from a supply, thread nipper mechanism for preventing the drawing of thread into the thread system, means. for automatically rendering said thread nipper mechanism effective during the thread drawing action of said loop taker upon the'last stitch of the sewing cycle, and a stop motion 'mechanismautomatically effective upon the last stitch of the sewing cycle for stopping the forward motion of said sewing machine at a point in the stitch-forming cycle where, after said thread nipper mechanism has been rendered effective, said loop taker has been advanced through the thread drawing action thereof sufficient to stress the thread in the system beyond the breaking point and thereby sever the same.

2. In a cyclically-operated single thread chain stitch sewing machine having stitching mechanism including the invention what needle in the formation of stitches, said looper having a V stitch forming cycle wherein a loop of thread thrown by said needle is seized by said looper and thereafter expanded by a thread drawing action during which thread is drawn into the thread system from a supply, thread nipper mechanism for preventing the drawing of thread into the thread system, means for automatically rendering said thread nipper mechanism effective during the read drawing action of said looper upon the last stitch of the sewing cycle, and a stop motion mechanism automatically eifective upon the last stitch of the sewing cycle for stopping the forward motion of said sewing machine at a point in the stitch-forming cycle Where, after said thread nipper mechanism has been rendered eifective said looper has been advanced through the thread drawing action thereof suflicient to stress the thread in the system beyond the breaking point and thereby sever the same.

3. In a cyclically-operated sewing machine having stitching mechanism including a needle and a loop taker cooperating with said needle in the formation of stitches, said loop taker having a stitch-forming cycle wherein a loop of thread thrown by said needle is seized by said loop taker and thereafter expanded by a thread drawing action during which thread is drawn into the thread system from a supply, a stop motion mechanism for stopping said sewing machine at the completion of a sewing cycle with said stitching mechanism in a predetermined stop position wherein said loop taker has effected loop seizure and is in the initial portion of said thread drawing action and for providing an overthrow of said machine from said predetermined stop position, thread nipper mechanism for preventing the drawing of thread into the thread system, means for rendering said stop motion mechanism ineffective to provide for operation of the sewing machine, means for automatically rendering said stop motion mechanism effective at the completion of the sewing cycle, and means for automatically rendering said thread nipper mechanism effective prior to the completion of the overthrow of the machine from said predetermined stop position wherein said overthrow will advance said loop taker through the thread drawing action thereof sufiicient to stress the thread in the system beyond the breaking point and thereby sever the same.

4. In a cyclically-operated single thread chain stitch sewing machine having stitching mechanism including a needle and a wing-type looper cooperating with the needle in the formation of stitches, said looper having a stitch-forming cycle wherein a loop of thread thrown by said needle is seized by said looper and thereafter expanded by a thread drawing action during which thread is drawn into the thread system from a supply, a stop motion mechanism for stopping said sewing machine at the completion of a sewing cycle with said stitching mechanism in a predetermined stop position wherein said looper has eifected loop seizure and is in theinitial portion of said thread drawing action and for providing an overthrow of said machine from said predetermined stop position, thread nipper mechanism for preventing the drawing of thread into the thread system, means for rendering said stop motion mechanism inefiective to provide for operation of the sewing machine, means for automatically rendering said stop motion mechanism eifective at the completion of the sewing cycle, and means for automatically rendering said thread nipper mechanism eifective prior to the completion of the overthrow of the machine from said predetermined stop'position wherein said overthrow will advance said looper through the thread drawing action thereof sufficient to stress the thread in the system beyond the breaking point and thereby sever the same.

5. In a cyclically-operated sewing machine having stitching mechanism including a needle and a loop taker cooperating with said needle in the formation of stitches, said loop taker having a stitch-forming cycle wherein a loop of thread thrown by said needle is seized by said loop taker and thereafter expanded by a thread drawing action during which thread is drawn into the system from a supply, a stop motion mechanism for stopping said sewing machine at the completion of a sewing cycle With said stitching mechanism in a predetermined stop position wherein said loop taker has eifected loop seizure and is in the initial portion of said thread drawing action, said stop motion mechanism comprising means positively engaged at said predetermined stop position and means providing for resiliently resisted displacement of said stop means from said predetermined stop position to absorb the inertia of and thereby stop said machine and thus define an overthrow from said predetermined stop position, thread nipper mechanism for preventing the drawing of thread from the source, means for rendering said stop motion mechanism inefiective to provide for operation of the sewing machine, means for automatically rendering said stop motion mechanism efiective at the completion of the sewing cycle to stop said machine, and means for automatically rendering said thread nipper mechanism effective prior to the completion of the overthrow of the machine from said predetermined stop position wherein said overthrow will advance said loop taker through the thread drawing action thereof sufiicient to stress the thread in the system beyond the breaking point and thereby sever the same.

6. In a cyclically-operated single thread chain-stitch sewing machine having stitching mechanism including a needle and a wing-type looper cooperating with the needle in the formation of stitches, said looper having a stitch-forming cycle wherein a loop of thread thrown by said needle is seized by said looper and thereafter expanded by a thread drawing action during which thread is drawn into the thread system from a supply, a stop motion mechanism for stopping said sewing machine at the completion of a sewing cycle with said stitching mechanism in a predetermined stop position wherein said looper has effected loop seizure and is in the initial portion of said thread drawing action and for providing an overthrow of said machine from said predetermined stop position, thread nipper mechanism for preventing the drawing of thread into the thread system, means for rendering said stop motion mechanism ineffective to provide for operation of the sewing machine, means for automatically rendering said stop motion mechanism effective at the completion of the sewing cycle, and means for automatically rendering said thread nipper mechanism eifective prior to the completion of the overthrow of the machine from said predetermined stop position wherein said overthrow will advance said looper through the thread drawing action thereof sufiicient to stress the thread in the system beyond the breaking point and thereby sever the same.

References Cited in the file of this patent UNITED STATES PATENTS 

